Nutrients necessary for human to live are introduced into the body, usually, by food intake from the mouth. For those patients who have difficulty in swallowing foods, those patients with a chronic bowel disease and those patients who have difficulty in taking foods from the mouth because of high age or the like, various commercial fluid diets are used (Non-Patent Document No. 1). These fluid diets are thick (highly concentrated) and prepared at 1 kcal/ml or more. Therefore, administration of such fluid diets alone cannot supply the amount of water necessary per day, and it is necessary to administer some water between meals. Administration of water between meals imposes considerable labor on caregivers or nurses.